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Fraser
2004-Oct-22, 03:53 PM
SUMMARY: When developing his General Theory of Relativity, Albert Einstein predicted that the Earth should drag space and time around with it as it rotates on its access. NASA's Gravity Probe B spacecraft was launched earlier this year to help confirm this prediction, but an international team of researchers has beaten the spacecraft to a conclusion. By carefully tracking the position of the LAGEOS and LAGEOS 2 satellites - beachball-sized spheres covered in mirrors - they discovered that their orbit is being shifted by about two metres a year by this dragging effect by the Earth's gravity, almost exactly what was predicted by Einstein.

What do you think about this story? Post your comments below.

Guest_John
2004-Oct-22, 04:53 PM
It's access?

StarLab
2004-Oct-22, 05:15 PM
I still think that the neccessary confirmation of Einstein's theory will come from GPB...if GPB comes up with the same results, the credit will go to GPB, I think...if not, I think one of the two parties must recheck their measurements...because, I think, the GPB has more margin for error.

antoniseb
2004-Oct-22, 05:20 PM
Originally posted by StarLab@Oct 22 2004, 05:15 PM
I think, the GPB has more margin for error.
Do you have any reason for thinking that Gravity-Probe B will have more error in its measurements than this experiment based on published data?

StarLab
2004-Oct-22, 05:56 PM
Well, I think the GPB was designed to be super-accurate, so it would be a sad thing if we do not get such a result.

Fraser
2004-Oct-22, 06:17 PM
oops, it should be "axis", not access.

Z28Jerry
2004-Oct-23, 10:22 AM
Beside's confirming a prediction based on a theory, what does this mean? Is this information something we can use to our advantage in the future, or is it just about understanding the universe?

antoniseb
2004-Oct-23, 12:51 PM
Originally posted by Z28Jerry@Oct 23 2004, 10:22 AM
Is this information something we can use to our advantage in the future, or is it just about understanding the universe?
At the moment, it is probably simply about understanding the universe. If confirmed, it eliminates numerous alternative theories of gravitation, but it will not help to design a better blender.

GOURDHEAD
2004-Oct-25, 02:47 AM
Here (http://en.wikipedia.org/wiki/Frame_dragging) and
here (http://antwrp.gsfc.nasa.gov/apod/ap971107.html) are some references to frame dragging which leave me uninformed about what effect is being measured and how those who measure it can discount inhomogeneities including those due to the stochastic distribution of relativistic velocities of various mass accumulations within, for example, accretion disks containing components orbiting at relativistic speeds and the attendant interplay of the electric and magnetic fields. How does the rate of spin affect frame dragging? How can one be sure an effect from either electric or magnetic fields is not dominating the deviation from the frame-dragging-free cases? The Lorentz transformations affecting mass and time must surely guarantee that the effect does not vary as a linear function of spin rate. In a hypothetical homogeneously "pure" rapidly spinning object, it seems counterintuitive that frame dragging would occur.

Neutron stars (and black holes??) have been observed to have geometric spin axes that are not aligned with their magnetic axes. Assuming that accretion disks align themselves approximately perpendicular to the spin axes, what sort of precession of the accretion disk should one expect and how could one tell that it had a frame dragging component?

Is it obvious to each except me whether "the frame" outruns the orbiting mass creating the appearance that the mass is lagging or does the frame dragging effect impart additional energy to the orbiting object such that it appears to speed ahead?

Paul21
2004-Oct-25, 11:59 AM
["We found the plane of the orbits of LAGEOS I and II were shifted about six feet (two meters) per year in the direction of the Earth's rotation," Pavlis said. "Our measurement agrees 99 percent with what is predicted by general relativity, which is within our margin of error of plus or minus five percent. Even if the gravitational model errors are off by two or three times the officially quoted values, our measurement is still accurate to 10 percent or better." Future measurements by Gravity Probe B, a NASA spacecraft launched in 2004, should reduce this error margin to less than one percent. This promises to tell researchers much more about the physics involved.(1)]

The physics involved is that what rotates the earth creates also what we see as ambient space. Its 3D-spiral swirl of basic matter spreads far beyond the orbit of the moon and drives the moon around the earth [2]. The differential rotation of this faster inward moving 3D-spiral swirl rotates the planes of the orbits of LAGEOS I and II satellites. The discovered 3D-spiral code of reality [2] is in agreement with this finding. The assumptions on which the general relativity is based are superfluous and so is this conceived before the age of spacecraft and chaos theory.

1. http://www.nasa.gov/vision/earth/lookingat...earth_drag.html (http://www.nasa.gov/vision/earth/lookingatearth/earth_drag.html)

2. Savov, E., Theory of Interaction, Geones Books, 2002.

GOURDHEAD
2004-Oct-25, 12:44 PM
Excerpt 1 from link to NASA report


"We found the plane of the orbits of LAGEOS I and II were shifted about six feet (two meters) per year in the direction of the Earth's rotation," Pavlis said. "Our measurement agrees 99 percent with what is predicted by general relativity, which is within our margin of error of plus or minus five percent. Even if the gravitational model errors are off by two or three times the officially quoted values, our measurement is still accurate to 10 percent or better." Future measurements by Gravity Probe B, a NASA spacecraft launched in 2004, should reduce this error margin to less than one percent. This promises to tell researchers much more about the physics involved.



Excerpt 2 from NASA

NASA and Stanford University, Palo Alto, Calif. developed Gravity Probe B. It will precisely check tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting 400-miles directly over the poles. The experiment will test two theories relating to Einstein's Theory of General Relativity, including the Lense-Thirring Effect. These effects, though small for Earth, have far-reaching implications for the nature of matter and the structure of the universe.

GOURDHEAD
2004-Oct-25, 01:23 PM
Excerpt 1 from link to NASA report
QUOTE
"We found the plane of the orbits of LAGEOS I and II were shifted about six feet (two meters) per year in the direction of the Earth's rotation," Pavlis said. "Our measurement agrees 99 percent with what is predicted by general relativity, which is within our margin of error of plus or minus five percent. Even if the gravitational model errors are off by two or three times the officially quoted values, our measurement is still accurate to 10 percent or better." Future measurements by Gravity Probe B, a NASA spacecraft launched in 2004, should reduce this error margin to less than one percent. This promises to tell researchers much more about the physics involved.

Excerpt 2 from NASA
QUOTE
NASA and Stanford University, Palo Alto, Calif. developed Gravity Probe B. It will precisely check tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting 400-miles directly over the poles. The experiment will test two theories relating to Einstein's Theory of General Relativity, including the Lense-Thirring Effect. These effects, though small for Earth, have far-reaching implications for the nature of matter and the structure of the universe.


[Oops I inadvertantly added an incomplete reply in the previous attempt]

In excerpt 1 it seems the orbiting object outruns that of one orbiting a frame-dragging-free mass. Why does the orbit remain planar? One (at least one, namely me) would expect the effect to vary with latitude.

In excerpt 2 I assume the orbital plane contains the spin axis of the earth, at least at the beginning. Has the predicted variation due to the Lense-Thirring Effect been published?

GOURDHEAD
2004-Oct-25, 04:13 PM
Is it commonly accepted that the Lense-Thirring Effect applies to greatly extended rotating collections of mass such as superclusters of galaxies and that it extends outward from the center of mass over immeasurably large distances? Could it possibly contribute to cosmological reddening of light by modulating the "local" curvature of spacetime in the affected regions?

bunny
2004-Oct-26, 02:22 PM
I personally think this is a redundant exercise. To get a proper idea of frame dragging you would need to have an object a long distance away, in a perfect geostationary orbit (initially) and for that object to experience no drag (i.e. in a perfect vacuum) other than 'frame drag'. None of these premises can be achieved, you cannot put an object in a perfect geostationary orbit, the orbit must be far enough out of the planets atmosphere (how far does that theoretically reach?), not be influenced by earths magnetic field, not affected by the solar wind, not affected by the moons gravity, not affected by the changes inside the earth (magma boles).

As gourdhead points out I would also expect to see a change with latitude since the earth turns slower at the poles than at the equator.

As for the measured drag of 2 metres a year, that is a huge distance considering the effect we are trying to measure is extremely small.

Janice
2004-Oct-27, 04:48 AM
:huh: Doesn't it all seem like such a waste? I mean all the work and innovation and research that went into GPB and frame dragging already got proven.
Oh well maybe it's just me. :unsure:

GOURDHEAD
2004-Oct-27, 01:40 PM
"We found the plane of the orbits of LAGEOS I and II were shifted about six feet (two meters) per year in the direction of the Earth's rotation," Pavlis said. "Our measurement agrees 99 percent with what is predicted by general relativity, which is within our margin of error of plus or minus five percent.

Note that the orbital plane of the object appears to move ahead of where it would be if the Newtonian view of gravity were the controlling force and that an acceleration of 2 meters per orbital distance per year is implied. I assume the effect applies to an object in a near equatorial orbit. An object orbiting with greater velocity than is commensurate with its distance from its primary could emulate dark matter. If this tiny acceleration moves the orbiting object outward, it would emulate dark energy by appearing to expand the universe (actually the distance between objects within it). If this effect is real, what is its strength at the moon's orbit or at the earth's equator? The effect on something that has been orbiting for 3 or 4 billion years should be quite noticeable.

This concept, assuming I understand it, is not very appealing intuitionally.

Xmo1
2004-Oct-30, 11:42 AM
If these measurements can be done then it might be helpful to know if the center of mass of the Earth is the same as the center of gravity, or if the the liquid core of the Earth might contain a solid 'nodule' more dense than its surrounding environment like the yellow part of an egg, which may rotate at a different speed through the fluid.

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